Aside from one notable exception, the IRFU have steadfastly refused to issue an exemption to allow Irish internationals based overseas to represent their country.
Jonathan Sexton's stint in Paris aside, when he was unchallenged as Ireland's pre-eminent out-half, the consistent message to players, from Ian Madigan to Simon Zebo, Marty Moore to Donnacha Ryan, is that the right to a green jersey is forfeited once a provincial jersey is forsaken.
It is a policy that successive Ireland coaches have adhered to, along with their paymasters, despite the controversial policy of recruiting overseas players to represent Ireland, which to some remains a deeply hypocritical stance.
But could that change in 2021 as the IRFU prepares to wield necessary financial cuts in forthcoming contract negotiations as a result of straitened Covid restrictions on their income streams?
While there are similarly constricted economic uncertainties prevailing in the familiar escape routes for Irish players, primarily in England and France, there are still possibilities there, as recent transfer movements indicate, while Japan is always an option for a swift and lucrative pay packet.
As of yet, there have been no scare stories planted by twitchy agents in the Irish media indicating that a potential player drain is imminent but, with wages likely to be reduced across the board, some movement must be inevitable.
Most may be at the lower end of the spectrum - as the speculation swirling around Munster out-half Ben Healy illustrates, however obliquely - but it would be unusual were one or two established players not to become linked with moves away in what will be an uncertain year for rugby establishments in all jurisdictions.
The IRFU will retain their infamous unwritten rule as a deterrent when contract negotiations start in earnest, but it may become a much blunter instrument should what they are offering fall far short of what their players are seeking.
"Are the likes of Peter O'Mahony or Tadhg Furlong going to get €500k contracts?" muses former international Stephen Ferris, Premier Sports analyst for the forthcoming Guinness PRO14 derbies. "If they want to play in Ireland, they have to be willing to take a drop in wages. Are you selfish and move along?
"Maybe some players are thinking like that. But rugby is a team game and you look at Munster last weekend - they weren't playing for contracts, they were playing for each other.
"It's in the back of their minds. You just want to play away every week. Everyone is keeping quiet about it.
"Maybe the IRFU are hoping it will be sorted. But maybe players will get itchy feet. And a few might disappear at the end of the season.
"It's a tricky one. I personally feel that seeing Simon Zebo going way and breaking the mould is a good thing. Donnacha Ryan was offered a crap contract and wanted to go away, I've respect him for that. They know they won't play for Ireland. The problem is more and more players will go away, then the logistics all add up.
"It's a lot easier to keep tabs on them playing here. I'm not sure if that's an idea. Who knows what might happen? If eight or nine players go away, I'd be looking to bring them in."
With so much uncertainty, Darren Cave believes that the IRFU need to cover all options; one of them could be an escape clause, perhaps something similar to the "Giteau rule", devised in Australia for eponymous centre Matt, and subsequently widely copied elsewhere, which allows senior internationals the right to pursue a career abroad without being barred from international duty.
"We don't know any public details but if you take the Scottish Union as an example, it must have been discussed after Adam Hastings was allowed to join Finn Russell and Jonny Gray overseas.
"You can bring other guys through at the same time. I'm not saying you apply it across the board, but sometimes drastic times need drastic measures.
"I would be reviewing the policy. So instead of having a blanket ban, could we see can we get players to clubs who can look after them?
"It wouldn't be hard to knock three or four million euro off the wage bill by losing 10 players. I'm not sure that there is a policy change coming but it should be discussed."
Ferris also believes that Ulster's expensive import, Marcel Coetzee, sorely missed as his side crashed out of the Champions Cup, may be tempted by a move overseas.
"It will be extremely difficult to keep him. He showed good faith re-signing after his knee injury. If I was him, to set up his family, if the numbers don't add up at Ulster, I certainly would be making a move."